After weeks of focusing on a group of current and former elected officials in his search for a running mate, Donald Trump is increasingly intrigued by the idea of tapping retired Lt. Gen. Michael T. Flynn to project strength and know-how on national security, according to four people familiar with the vetting process.

Flynn, a registered Democrat but fierce critic of President Obama, previously ran the Defense Intelligence Agency.

The people who spoke with The Washington Post on Saturday did so on the condition of anonymity to discuss their private conversations in recent days with Trumpís confidants and campaign aides.